Differential pressure metering device

ABSTRACT

A metering end cap provided to the neck of a flexible container containing a fluid and intended to transfer, at will, an amount of fluid from an upstream space towards a downstream space, this end cap including a chamber in which is disposed a movable valve normally biased towards a rest position and operationally moved towards an end position. The valve isolates the upstream space and the downstream space from each other in its end position and only in this position, and the outlet of the chamber communicates with the upstream space for any position of the valve other that its end position.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 14/189,605,filed Feb. 25, 2014, which in turn is a division of application Ser. No.13/127,972 filed Jul. 27, 2011, which is a National Phase entry of PCTApplication No. PCT/FR2009/001277, filed Nov. 4, 2009, which claimspriority from French Application No. 0806164, filed Nov. 5, 2008, eachof which is hereby fully incorporated herein by reference.

TECHNICAL FIELD

Embodiments of the present invention relate to the production of devicesfor metering liquid or pasty fluids, such as, in particular, cosmetic,food or cleaning fluids, such fluids being generally contained in aflexible flask and being delivered in calibrated measured amounts eachtime a user presses this flask.

More precisely, embodiments of the invention relate to a metering devicefor transferring, from an upstream space towards a downstream space, apredetermined volume of liquid or pasty fluid in response to a rise inpressure of this fluid in the upstream space, this device including atleast a hollow body and a valve, the hollow body delimiting at leastpartially a chamber equipped with an inlet and an outlet, the valvebeing movable with respect to the hollow body between a rest position,towards which this valve is biased by a return force, and an endposition, which is spaced from the rest position and towards which thisvalve is selectively biased by the fluid flowing from the upstream spacetowards the downstream space, the upstream space extending at leastoutside the chamber at the inlet side thereof, and the downstream spaceextending at least outside the device and the chamber at the outlet sidethereof.

BACKGROUND

Such a device is for example known from patent document EP 0,995,976entitled “Metering end cap and container equipped with a metering endcap according to the invention”. The device described in this documenthas a large number of molded or blown parts, the manufacturing andassembly tolerances of which are very low. Moreover, the design of thisdevice requires guiding the valve, called “metering piston”, both on itsinternal diameter and on its external diameter, which causes thegeneration of high friction forces.

U.S. Pat. No. 4,582,230, entitled “Metering Device”, also describes afluid metering device, this metering device implementing a lock of whichvolume corresponds to the unitary metered amount. The outlet aperture ofthe metering device is selectively shut-off by a piston connected by acylindrical rod to a ball controlling the opening of the lock, on theupstream space side delimited by a bottle. When the bottle is held in avertical position, the piston closes the pourer of the metering device.When the bottle is being overturned, the piston keeps on maintaining thepourer closed, while the liquid enters in the lock. Once the bottle isin the vertical position, the ball closes the inlet of the lock, whereasthe piston is descended, opening the pourer and releasing the liquidcontained in the lock.

In addition to the fact that this solution also requires implementing alarge number of parts, the result sought can only be obtained by slowlyreversing the bottle, so that the tank fills in before the ball comes toclose the liquid inlet in the tank, and before the piston releases theliquid contained in the tank. In addition, such a device is not adaptedto the metering of viscous fluids.

SUMMARY

In this context, an embodiment of the present invention is a meteringdevice free from at least one of the aforementioned defects.

To this end, embodiments of the invention include a valve that isolatesthe upstream space and the downstream space from each other in its endposition and only in this position, and a chamber outlet thatcommunicates with upstream space for any position of the valve otherthan its end position.

With this arrangement, the fluid traversing the hollow body under theeffect of a pressure increase at the chamber inlet causes the valve tomove from its rest position to its end position, and the volume of fluiddelivered from when the valve leaves its rest position and when thisvalve reaches its end position is equal to the volume of fluid whoseflow is necessary to operate this displacement of the valve.

In a possible embodiment, the valve includes at least a diaphragmmovable in translation with respect to the hollow body, and the returnforce at least partially includes an elastic return force.

In this case, embodiments of the invention include at least an elastictab attaching the valve to the hollow body, that the hollow body, thevalve, and each elastic tab be integrally made from an elastic material,and that the return force be exerted by each elastic tab.

In another possible embodiment, the valve includes at least anarticulated shutter, rotationally movable with respect to the hollowbody, the return force at least partially comprising an elastic returnforce.

Embodiments of the invention can also include a sealing seat whichsurrounds a fluid passage disposed between the upstream space and thedownstream space, and on which the valve rests in its end position.

The manufacturing of an embodiment of the invention can be facilitatedby providing the embodiment of the invention with a plug inserted in thehollow body, this plug having bored therein a flow-through openingforming the chamber outlet.

In a more advanced embodiment of the invention, it is possible toprovide the metering device such that it further includes a piston and aspring, that the piston be slidingly assembled in the hollow body andbears said valve, and that the spring be preloaded in compression anddisposed between the plug and the piston.

If the viscosity of the fluid to be delivered is relatively low, it canbe judicious to provide the chamber outlet such that it is bored in anelastically deformable wall and that it has a flow cross-sectionreversibly increasing under the effect of the fluid pressure.

In other possible embodiments of the invention, the density of the valveis lower than one so the valve can float in the fluid, the return forcebiasing this valve towards its rest position thus being at leastpartially composed of a buoyancy exerted on this valve which, inoperation, soaks in the fluid to be delivered.

Embodiments of the invention may constitute a complete operational unit,in which case, it further includes a container provided with a neck,this container intended to contain the fluid and delimiting a variablevolume upstream space, the rise in fluid pressure being obtained byreducing the upstream space volume, for example, by deforming thecontainer in the case where it is flexible, and the hollow body beingsealingly disposed in this container neck.

Other features and advantages of the invention will become more apparentfrom the following description thereof, given only for illustrative andin no way restrictive purposes, with reference to several embodimentsillustrated in the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an axial cross-sectional view representing an embodiment ofthe invention in which the valve is formed by a spherical floater;

FIG. 2 is an axial cross-sectional view representing an embodiment ofthe invention in which the valve is formed by a cylindrical floater witha truncated head;

FIG. 3a is an axial cross-sectional view representing an embodiment ofthe invention in which the valve is formed by a floater biased towardsits rest position by a spring;

FIG. 3b is a top view of a valve which may be used in the particularembodiment constituting an alternative of FIG. 3 a;

FIG. 4 is an axial cross-sectional view representing an embodiment ofthe invention in which the valve is formed by a floater maintained inits rest position by a semi-rigid tab;

FIG. 5a is an axial cross-sectional view representing an embodiment ofthe invention in which the chamber outlet is formed by a cruciformflow-through opening;

FIG. 5b is a front view of the outlet of the cruciform chamberillustrated in FIG. 5 a;

FIG. 6a is an axial cross-sectional view representing an embodiment ofthe invention in which the valve is formed by a diaphragm illustrated inits rest position;

FIG. 6b is an elevation side view of the embodiment of the inventionillustrated in FIG. 6 a;

FIG. 6c is another axial cross-sectional view of the embodiment of theinvention illustrated in FIG. 6a , in which the valve is represented inits end position;

FIG. 6d is an elevation top view of the embodiment of the inventionillustrated in FIG. 6 b;

FIG. 7a is an axial cross-sectional view representing an embodiment ofthe invention in which the valve is formed by a single shutterillustrated in dotted lines in its rest position and in solid lines inan intermediate position;

FIG. 7b is an axial cross-sectional view of the embodiment of theinvention illustrated in FIG. 7a , in which the valve is represented inits end position;

FIG. 8a is an axial cross-sectional view representing an embodiment ofthe invention in which the valve is formed by a diaphragm illustrated inits rest position, and in which the chamber is closed by the diaphragmassociated with a piston and has a variable volume, this chamber beingrepresented with its maximum volume;

FIG. 8b is an axial cross-sectional view of the embodiment of theinvention illustrated in FIG. 8a and seen in a transient state prior tothat which is illustrated in FIG. 8a , the valve being represented inits end position and the chamber being still represented with itsmaximum volume;

FIG. 8c is an axial cross-sectional view of the embodiment of theinvention illustrated in FIGS. 8a and 8b and seen in a transient stateprior to that which is illustrated in FIG. 8b , the valve being stillrepresented in its end position, and the chamber being represented withits minimal volume;

FIG. 8d is an axial cross-sectional view of the embodiment of theinvention illustrated in FIGS. 8a to 8c and seen in a transient stateprior to that which is illustrated in FIG. 8c , the valve being againrepresented in its rest position, whereas the chamber is stillrepresented with its minimal volume;

FIG. 8e is an axial cross-sectional view of the embodiment of theinvention illustrated in FIGS. 8a to 8d and seen in a stable stateposterior to that which is illustrated in FIG. 8d and identical to theinitial state illustrated in FIG. 8a , the valve being returned back toits rest position, and the chamber having resumed its maximum volume;

FIG. 8f is a top view of the embodiment of the invention illustrated inFIG. 8 e;

FIG. 9a is an axial cross-sectional view representing an embodiment ofthe invention in which the valve is formed by a double shutterillustrated in its end position, and in which the chamber is closed bythis double shutter associated with a piston, this chamber having avariable volume and being represented with its minimal volume;

FIG. 9b is an axial cross-section of the embodiment of the inventionillustrated to the FIG. 9a and seen in a stable initial state, the valvebeing represented in its rest position, and the chamber beingrepresented with its maximum volume;

FIG. 9c is a side view of the piston and valve of the embodiment of theinvention illustrated in FIGS. 9a and 9b , the valve being representedin solid lines in its rest position, and, in dotted lines, in anintermediate position and in its end position;

FIG. 9d is a top view of the piston and of the valve of the embodimentof the invention illustrated in FIGS. 9a to 9c , the piston and thevalve being represented in two of the positions they occupy in FIG. 9 c;

FIG. 10a is an axial cross-sectional view representing an embodiment ofthe invention in which the valve is formed by a single shutterillustrated in its rest position, and in which the chamber is closed bythis shutter associated with a piston, this chamber having a variablevolume and being represented with its maximum volume;

FIG. 10b is a top view of the piston and the valve of the embodiment ofthe invention illustrated in FIG. 10a , the piston and the valve beingrepresented in the position they occupy in FIG. 10 a;

FIG. 10c is an axial cross-sectional view of the embodiment of theinvention illustrated in FIGS. 10a and 10b , the valve being representedin its end position, and the chamber being represented with its minimalvolume; and

FIG. 10d is a top view of the piston and the valve of the embodiment ofthe invention illustrated in FIGS. 10a to 10c , the piston and the valvebeing represented in the position they occupy in FIG. 10 c.

DETAILED DESCRIPTION OF THE DRAWINGS

As previously stated, an embodiment of the invention relates to ametering device for transferring, from an upstream space E1 towards adownstream space E2, a predetermined volume of liquid or pasty fluid inresponse to a rise of fluid pressure in the upstream space E1.

As shown in particular on FIGS. 1 to 3 a, 4, 6 a, 7 a, 8 a, 9 b and 10a, an embodiment of the invention includes at least a hollow body 1 anda valve 2.

An embodiment of the invention further includes a container 8(represented only partially on the figures) for containing a fluid to bedispensed, and provided with a neck 80 which is the unique outlet forthe fluid.

The internal volume delimited by this container, which constitutes atleast the upstream space E1, has a variable capacity.

To this end, the container may for example include a flexible andelastically deformable wall, so that a pressure exerted on this wall bya user causes a transient reduction of the volume of the upstream spaceE1 and a concomitant rise in the pressure of the fluid contained in thecontainer.

Alternatively, the container may be only formed with rigid walls, whileincluding a piston which may be actuated by the user to cause atransient reduction of the upstream space E1 volume and a concomitantrise in the pressure of the fluid contained in this container.

The hollow body 1 is sealingly disposed in the neck 80 of this container8. In particular, the hollow body 1 can be forcibly inserted into neck80 until a stopper 9 of the hollow body presses against this neck.

The hollow body 1, of which shape is substantially cylindrical, at leastpartially delimits a chamber 100 provided with an inlet 5 and an outlet6.

Valve 2 is movable with respect to hollow body 1 between a rest positionillustrated, for example, on FIGS. 1, 2, 3 a, 4, 6 a, 6 b, 7 a (indotted lines), 8 a, 8 th, 9 b and 10 a, and an end position illustrated,for example, on FIGS. 6c, 7b, 8b, 8c, 9a and 10c , which is spaced apartfrom the rest position.

Valve 2 is biased towards its rest position by a return force, andbiased towards its end position, during application of a differentialpressure between the chamber inlet 5 and the chamber outlet 6, the fluidflowing from the upstream space E1 towards the downstream space E2,upstream space E1 extending at least outside chamber 100 at its inlet 5side, and the downstream space E2 extending at least outside themetering device and from chamber 100 at its outlet 6 side.

In its typical rest position, the container or flask 8 is positionedvertically so that its neck 80 is turned downwards, the fluid to bedispensed thus spontaneously tends to flow by gravity from the upstreamspace E1 towards downstream space E2, and from the inlet 5 of chamber100 towards the outlet 6 of this chamber.

According to an embodiment of the invention, valve 2 isolates theupstream space E1 and the downstream space E2 from each other in its endposition, and only in this position.

In addition, the outlet 6 of chamber 100 communicates with upstreamspace E1 for any position of valve 2 other that its end position.

As shown in particular in FIGS. 1, 2, 3 a, 4, 5 a, 6 a, 6 c, 7 a, 7 b, 8a, 8 b, 10 a and 10 c, valve 2 can for example fulfill its function bycooperating with a sealing seat 30 which surrounds a fluid passagedisposed between upstream space E1 and downstream space E2, and on whichthis valve 2 presses in its end position.

Moreover, as shown in FIGS. 1, 2, 3 a, 8 a to 8 f, 9 a, 9 b, 10 a and 10c, an embodiment of the invention may include a plug 3 inserted in thehollow body 1, this plug having drilled therein a flow-through openingforming the outlet 6 of chamber 100.

FIGS. 1 to 5 b illustrate embodiments of the invention in which valve 2has an average density lower than that of the fluid to be dispensed, andtypically a density lower than one.

In this case, valve 2, when it soaks in the fluid to be dispensed,behaves like a floater, so that the return force which biases this valvetowards its rest position is at least partially composed the buoyancyexerted thereon.

As an extension of this description of the embodiments of FIGS. 1 to 5b, words “upper” and “lower”, to indicate relative directions orpositions, will be used in their common meaning, i.e. with reference tothe application direction of the terrestrial gravity, and thusrespectively to a upper/lower altitude with respect to the ground level.

Moreover, the container or flask 8 will be regarded to as being orientedsuch that its neck 80 is aimed downwards.

In the first detailed embodiment illustrated in FIG. 1, the hollow body1, for example of a cylindrical shape and made from plastic, contains,as valve 2, a hollow and spherical floater.

This hollow body 1 is forcibly inserted in neck 80 of container 8containing the fluid to be metered until a stopper 9 of this body 1comes into contact with this neck.

In addition, plug 3 is forcibly inserted in the lower part of the hollowbody 1 until a stopper 7 of this plug 3 comes into contact with thisbody 1.

The inlet 5 of chamber 100 has the shape of an opening provided in thehollow body 1, and the outlet 6 of chamber 100 has the shape of anopening provided in plug 3.

The size and/or shape of the outlet of the fluid chamber 6 may thus bemodified at will by substituting the plug 3 inserted in neck 80 byanother plug 3 having a flow-through opening 6 of a different sizeand/or shape.

Two grooves 4, for example U-shaped and disposed at 90° from each other,are provided in the upper part of the hollow body 1 so as to avoidfloater 2 from sealingly shutting-off the inlet opening 5 of chamber100, which is located in the upper part of the hollow body 1.

The edge of the recessed part of plug 3 forms a sealing seat 30 makingit possible for floater 2, when it comes to rest on this seat 30 in itsend position under the effect of a fluid pressure rise in upstream spaceE1, to isolate this upstream space E1 from downstream space E2, and tostop the fluid flow through the calibrated opening 6 of chamber 100outlet.

The annular gap between the hollow body 1 and floater 2 is sized so asto allow a flow by gravity of the fluid under floater 2. Thus, as soonas the fluid pressure in the upstream space E1 is released, allowing thefluid to flow again under floater 2, this floater is subjected, as itsdensity is lower than that of the fluid, to a buoyancy which sendsfloater 2 back in contact with the upper part of the hollow body 1, i.e.in its rest position illustrated in FIG. 1.

To generate, within the fluid to be dispensed, the differential pressurenecessary to displace floater 2, the flow cross-section of opening 6 ofthe outlet of chamber 100 should be provided such that it is higher thanthe flow cross-section provided by the annular gap between the floater 2and the hollow body 1.

When a pressure is exerted on the flexible container 8 to expel thefluid contained in the upstream space E1, floater 2 is biased by thefluid moving to the bottom of the hollow body 1, while the majority ofthe fluid contained in chamber 100 between floater 2 and plug 3traverses the outlet opening 6 of the chamber. Then, floater 2 comes toabut against the plug on the sealing seat 30 which it seals, prohibitingexpelling more fluid. The subsequent release of pressure on container 8and thus in upstream space E1 creates a depression which, by a lightrising of the floater, causes air to enter into chamber 100.

The flexible container 8 can thus return to its rest position, and thefluid, which flows by gravity in the hollow body 1, makes floater 2 toascend at the upper position towards its rest position, under the effectof buoyancy.

FIG. 2 illustrates an embodiment of the invention which differs from theembodiment of FIG. 1 only by the fact that valve 2 has the shape of acylindrical floater 2 provided with a truncated upper part instead ofhaving the shape of a spherical floater. Insofar as, for a sameencumbrance inside chamber 100, this truncated head cylindrical floaterhas a higher volume than that of the spherical floater, the embodimentof FIG. 2 is more particularly adapted to the metering of low densityfluids.

In another embodiment of the invention, illustrated in FIG. 3a , ahelical spring 10 preloaded in compression is disposed between thebottom of plug 3 and floater 2, this floater 2 being thus biased towardsits rest position, abutting against the upper wall of the hollow body 1at the inlet opening 5, by a return force including both the buoyancyexerted on floater 2 by the fluid, and the elastic force exerted onfloater 2 by spring 10.

In an embodiment, the elastic force exerted by spring 10 on floater 2 issized to only compensate the weight of floater 2, spring 10 being onlyused to support the ascent of floater 2 when the fluid flows at thebottom of hollow body 1. This arrangement, which makes it possible toeasily overcome viscous frictions, is more particularly adapted if theviscosity of the fluid to be dispensed is high.

FIG. 3b illustrates an alternative of the embodiment of FIG. 3a , thatmay be implemented in the case illustrated on FIG. 3a and in whichfloater 2 has an upper part of truncated shape. According to thisalternative embodiment, the upper part of floater 2 comprises severalcircular notches 13 cut-out on the entire cylindrical height of floater2, so that the fluid can flow from container 8 towards chamber 100 whenfloater 2 is in its rest position. Nevertheless, these notches 13 aresized such that floater 2 is still able to seal the sealing seat 30 onceit reaches its end position. To this end, the minimum diameter of thecylindrical surface of floater 2, at the deepest locations of notches13, is higher than the diameter of the interior surface of plug 3.Moreover, as previously, the surface of the annular section definedbetween floater 2 and the interior of hollow body 1 remains lower thanthe surface of the outlet opening 6 of chamber 100, provided in plug 3.

FIG. 4 represents an embodiment of a metering device without the plugand in which the hollow body 1 is forcibly inserted into neck 80 of theflexible container containing the fluid until a stopper 9 of the hollowbody presses on neck 80. Owing to the absence of a plug, the outletopening 6 of chamber 100 is directly provided in the base of hollow body1. The sealing seat 30 is then directly formed by the edge of theopening 6, on which valve 2 comes to press sealingly in its endposition. The upper part of the cylindrical hollow body 1 is entirelyopen. A semi-rigid tab 11, for example, formed of a single piece withthe upper part of the wall of hollow body 1, covers the upper opening ofthis body 1 so that floater 2, once inserted under the semi-rigid tab11, remains trapped in the hollow body 1 despite the action of thedifferential pressures exerted in the fluid during the use of theflexible container. In other words, the insertion of the floater 2 underthe semi-rigid tab 11, or the withdrawal of this floater, can only beobtained by applying to tab 11 a deformation higher than that itundergoes in normal use of the metering device of embodiments of theinvention.

When container 8 is in the rest position, with the neck 80 orienteddownwards, the fluid contained in this container 8 flows by gravityuntil it fills chamber 100 delimited by the hollow body 1, so that thefloater is brought back to its rest position, by the effect of buoyancy,abutting against tab 11.

A pressure exerted on container 8 causes the fluid contained therein toflow towards neck 80. The moving fluid exerts a pressure on the floater2, which moves downwards while expelling, through the outlet opening 6,the fluid contained in chamber 100. Once floater 2 is resting againstseat 30 surrounding the outlet opening 6, this opening is sealed and theflow of fluid out of chamber 100 and towards downstream space E2 isstopped. The relief of the pressure on the surface of container 8produces a depression which causes air to enter inside hollow body 1,bringing back the container to its rest state. Owing to the annular gapbetween floater 2 and the interior wall of the cylindrical hollow body1, the fluid flows again in chamber 100 by gravity and passes underfloater 2, so that the buoyancy exerted on this floater 2 graduallybrings it back to its rest position, in abutment against the semi-rigidtab 11.

In an embodiment, the semi-rigid material constituting tab 11 isselected flexible enough to be able to undergo the necessary deformationto forcibly insert floater 2 in hollow body 1 without breaking, butsufficiently rigid so as not to undergo, under the effect of thebuoyancy exerted on floater 2, a deformation which would cause thefloater to escape from the hollow body when in its rest position inwhich it is pressed on this tab. The embodiment of FIG. 4 makes itpossible to produce the metering device in two molded parts, namely themain body 1 and tab 11 on one hand, and floater 2 on the other hand.

FIGS. 5a and 5b illustrate an alternative embodiment particularlyapplicable to the embodiment of FIG. 4 and particularly adapted to thecase where the fluid to be metered has a relatively low viscosity.

According to this alternative embodiment, the outlet of chamber 6 isbored in an elastically deformable wall and has a flow cross-sectionalarea reversibly increasing under the effect of the fluid pressure.

In this regard, the bottom 12 of hollow body, where the flow-throughopening 6 forming the outlet of chamber 100 is provided, is made from anelastically deformable material exhibiting a cruciform cut-out, andvalve 2 exhibits a cylindrical shape.

When the pressure exerted on the flexible container 8 causes floater 2to descend towards its end lower position to abut on seat 30, the thrustexerted by the fluid moving at the same time than floater 2 exerts onbottom 12 a pressure which deforms each part of the cruciform cut-out,so that the surface of outlet 6 of chamber 100 reversibly increases asan increasing function of this pressure.

Once abutting on the lower part in its end position, floater 2 sealsoutlet 6 and prevents any flow of fluid. Without external pressure, theonly force generated by the height of fluid in the container cannotovercome the elasticity of the flexible blades formed at the corners ofthe cruciform outlet 6 of chamber 100, the fluid being thus retained inthe metering device.

FIGS. 6a to 10d illustrate other possible embodiments of the invention,in which the density of valve 2 is not specified à priori and in anycase not necessarily lower than that of the fluid, this valve beingbiased towards its rest position by a return force of an exclusivelyelastic nature.

In the embodiment depicted in FIGS. 6a to 6d , valve 2 is formed by adiaphragm movable in translation with respect to hollow body 1, thisdiaphragm being connected to hollow body 1 by two elastic tabs 21diametrically opposite to each other, and the elastic return force ofthe valve being exerted by these tabs 21.

In this embodiment, the hollow body 1, the valve 2 and each elastic tab21 are preferably integrally formed from an elastic material.

The sealing seat 30, on which valve 2 rests in its end position, isformed on the upper part of the hollow body 1 and surrounds a fluidpassage disposed between upstream space E1 and downstream space E2 andforming the inlet 5 of chamber 100.

At rest, valve 2 occupies the position illustrated in FIGS. 6a and 6 b.

When the fluid in the upstream space E1 is subjected to a pressure whichpushes it towards outlet 6, the kinetic energy imparted to the fluidexerts on valve 2 a trailing force which biases it towards its endposition illustrated in FIG. 6c , the amplitude Fx of this trailingforce satisfying equation:

Fx=ρ·S·V ² ·Cx/2,

Where ρ represents the fluid density;

where S represents the master-torque of valve 2;

where V is the fluid speed; and

where Cx represent the trailing coefficient, related to the shape of thevalve.

As in the preceding embodiments, the fluid which traverses the hollowbody 1 under the effect of a pressure increase at the inlet 5 of chamber100 moves valve 2 from its rest position (FIG. 6a ) to its end position(FIG. 6c ), and the volume of fluid dispensed from when valve 2 leavesits rest position till when this valve 2 reaches its end position isequal to the volume of fluid whose flow is necessary to provide thisdisplacement of valve 2.

The embodiment depicted in FIGS. 7a and 7b differs from the embodimentdepicted in FIGS. 6a to 6d only by the fact that valve 2 is attached tothe hollow body 1 by a single elastic tab 21, this valve beingrepresented in its rest position in dotted lines on FIG. 7a and in itsend position on FIG. 7 b.

The embodiment depicted in FIGS. 8a to 8f uses the same valve 2 than theembodiment depicted in FIGS. 6a to 6d , as well as a plug 3 insertedinto hollow body 1 and carrying the outlet opening 6, as is particularlythe case in the embodiments depicted in FIGS. 1, 2 and 3 a.

On the other hand, the embodiment depicted in FIGS. 8a to 8f furtherincludes a piston 14 and a spring 15.

The piston 14 is slidingly mounted in hollow body 1 and valve 2 iscarried by the piston 14 by means of two elastic tabs 21 in the same waythan it was carried by hollow body 1 in the embodiment depicted in FIGS.6a to 6 d.

Piston 14 has a substantially annular form (FIG. 8f ) defining a sealingseat 30 around a fluid passage constituting the inlet 5 of chamber 100and which allows a selective communication between upstream space E1 anddownstream space E2.

Spring 15 is preloaded in compression and disposed between plug 3 andpiston 14, so that it tends to give to chamber 100 a maximum volume.

A stopper 140 is formed on the internal periphery of hollow body 1 tolimit the travel of piston 14 upwards by defining a maximum upperposition of this piston within hollow body 1.

The operation of the metering device according to an embodiment isillustrated in a sequential and chronological way in FIGS. 8a to 8 e.

FIG. 8a illustrates an embodiment of the invention in its stable restconfiguration, in which outlet 6 of chamber 100 communicates with inlet5 of this same chamber.

The pressure rise in container 8 causes the displacement of valve 2towards its end position illustrated in FIG. 8b , and in which thisvalve seals inlet 5 of chamber 100 while applying on the valve seat 30.

Insofar as the pressure of the fluid is thus exerted on the entiresurface of the piston 14 closed by valve 2, this piston moves downwardswhile reducing the volume of chamber 100, causing the discharge, throughoutlet 6, of the fluid contained in this chamber, and compressing spring15 correlatively, this movement being stopped when the piston 14 comesto rest against plug 3 (FIG. 8c ).

Following the relief of the fluid pressure in container 8, the elasticreturn force exerted by tabs 21 brings valve 2 back to its rest position(FIG. 8d ), thus allowing the fluid contained in container 8 to flow inchamber 100 by gravity.

As spring 15 biases piston 14 upwards, as well as to the fluid whichflows in chamber 100, chamber 100 resumes its initial maximum volume(FIG. 8e ), and the metering device thus returns back to its initialstable rest configuration.

Thus, the embodiment of FIGS. 8a to 8f makes it possible to dispense avolume of fluid including, in addition to the volume of fluid dispensedwhile the valve moves from its rest position to its end position, avolume of additional fluid exactly equal to the difference between themaximum volume of chamber 100, illustrated in FIGS. 8a and 8e , and theminimal volume of this chamber, illustrated in FIG. 8 c.

FIGS. 9a to 9d on one hand, and FIGS. 10a to 10d on the other hand,respectively illustrate two embodiments making also use of the principleof a chamber 100 closed by a piston 14 biased by a spring 15.

Moreover, in these two cases, the chamber is partially delimited by aplug 3 inserted in the hollow body 1, and the latter including aninternal peripheral stopper 140 making it possible to limit theascending travel of the piston 14.

In the embodiment depicted in FIGS. 9a to 9d , the piston 14substantially includes two mutually transverse beams 141 and 142, whichcan be particularly seen on FIG. 9d , and valve 2 is made up of twoshutters 22 articulated on beam 142 by means of respective hinge-formingelastic tabs 21, these shutters 22 being symmetrical from one anotherwith respect to the median plane of the beam 142 and the cylindricalhollow body 1.

In an embodiment, piston 14, each one of shutters 22 forming valve 2,and each one of the elastic hinge forming tabs 21 are integrally madefrom an elastic material.

The embodiment depicted in FIGS. 9a to 9d differs from all the otherpresented embodiments by the fact that valve 2, in its end position asrepresented on FIG. 9a , isolates upstream space E1 and downstream spaceE2 from each other not by being fixedly pressed on a sealing seat, butby a slipping bearing of the edge of each shutter 22 on the internalcylindrical wall of hollow body 1.

In the embodiment depicted in FIGS. 10a to 10d , valve 2 is made from asingle shutter 23, articulated on piston 14 by a single elastic tab 21.

Meanwhile, the embodiment depicted in FIGS. 10a to 10d substantiallydiffers from the embodiment depicted in FIGS. 8a to 8f by the fact thatvalve 2 is composed of a shutter 23 rotatably movable and not of adiaphragm movable in translation.

In an embodiment, the piston 14, the shutter 23 forming the valve 2, andthe elastic hinge-forming tab 21 are integrally made from an elasticmaterial.

As in the embodiment depicted in FIGS. 8a to 8f , the piston 14 of theembodiment depicted in FIGS. 10a to 10d has a substantially annular formdefining a sealing seat 30 around a fluid passage which constitutes theinlet 5 of the chamber 100 and which allows a selective communicationbetween upstream space E1 and downstream space E2.

1. A metering device securable to a container adapted to contain a fluidfor delivering a predetermined volume of the fluid in response to a risein pressure of the fluid contained in the container, this meteringdevice comprising: At least a hollow body at least partially insertableinto a neck of the container and comprising a fluid inlet and a fluidoutlet, the hollow body defining a chamber being in fluidiccommunication with the inlet and the outlet; and a buoyant valveinserted into the chamber and movable between a rest position and an endposition, the buoyant valve abutting the inlet when in the restposition, and substantially preventing the fluid from exiting themetering device from the outlet when in the end position, the buoyantvalve being movable from the rest position towards the end positionfollowing the rise in pressure of the fluid contained in the containerwhile some of the fluid is delivered via the outlet, and from the endposition towards the rest position when the rise in pressure is releasedwhile air enters the container via the outlet of the chamber.
 2. Themetering device of claim 1, wherein, when in the end position, thebuoyant valve abuts an edge of the fluid outlet, thereby preventing thefluid from exiting the metering device.
 3. The metering device of claim1, further comprising a sealing seat extending inwardly around the fluidoutlet, the buoyant valve abutting the sealing seat when in the endposition, thereby preventing the fluid from exiting the metering device.4. The metering device of claim 1, wherein the hollow body is providedwith a groove surrounding at least partially the fluid inlet so as toprevent the buoyant valve, when in the rest position, from sealinglyshutting-off the fluid inlet.
 5. The metering device of claim 1, furthercomprising a spring biasing the buoyant valve towards the rest position.6. The metering device of claim 1, wherein the buoyant valve comprises atruncated head cylindrical floater
 7. The metering device of claim 1,wherein the buoyant valve comprises a spherical floater.
 8. The meteringdevice of claim 1, wherein the buoyant valve is hollow.
 9. The meteringdevice of claim 1, wherein a neck of the container is orienteddownwardly during the rise in pressure of the fluid in the upstreamspace.